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2009 Honda Pilot 84-21 VSA Sensor Neutral Position not writing

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Jan 8, 2017, 7:08 AM

Post #1 of 3 (10645 views)
2009 Honda Pilot 84-21 VSA Sensor Neutral Position not writing Sign In

I have a 2009 Honda Pilot Touring 2WD 3.5 6cyl. 54,000 miles.

I rebuilt this car after it was wrecked in the front end. Body shop did the body work I took care of engine/sensors wiring. I replaced everything that had visible damage with new Honda parts. The area around the VSA modulator was not really impacted and the abs module is original. If memory serves me right I did change that harness that goes to abs modulator with a new one.
When I got the car from the insurance yard I noticed the right rear and front wheel sensors wires were cut assuming they cut them when lifting it with a fork loader. The wires were cut on the sensor side and not the car harness side. There was no obvious signs of damage or stress to the plug in harness clipped to the car so I could repair both by just buying new sensors.

Car runs great ....except after clearing all codes I get VSA and ABS light. Code reads 84-21 VSA Sensor Neutral Position not writing. I am using a Snap On Modis Scan Tool that is older but new to me so I am still learning its functions. Not sure if I can use this tool to adjust sensors or how that process would work or if it even applies.
Any ideas?

(This post was edited by cmb7684 on Jan 8, 2017, 7:17 AM)

Hammer Time
Ultimate Carjunky / Moderator
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Jan 8, 2017, 8:44 AM

Post #2 of 3 (10625 views)
Re: 2009 Honda Pilot 84-21 VSA Sensor Neutral Position not writing Sign In

Then system needs to do a memorization. I can't tell you if your snap-on is capable of doing that but I doubt it. You'll have to look through the menu when you have it hooked up to the car.

You may need to have it done by the dealer or someone with the correct equipment.


We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.


Jan 8, 2017, 9:30 PM

Post #3 of 3 (10599 views)
Re: 2009 Honda Pilot 84-21 VSA Sensor Neutral Position not writing Sign In

Ok I decided to go with it since the car has been running a good bit and any error codes should show up. I did a rescan for error codes of the ABS system. I still received only the 84-21 VSA Sensor Neutral Position not writing code as the only code. I guess this will be a good time to put the disclaimer that I have no idea what I am doing with cars and I am not a mechanic. This worked for me to get rid of the ABS VSA lights. I cannot even say for sure either of the systems are operating properly and that this is the proper fix or correct way to fix your vehicle.

With that said. I went into the menu on my scan tool that allows me to make adjustments. As it walks through the warnings it tells you that you are adjusting the wheel speed sensors. While I don't know for sure, it gives the impression that you are supposed to sync the sensors to the car as it walks you through. It also tells you not to do it unless certain conditions are met such as you changed out a faulty ABS part such as a wheel speed sensor or other components. it also says the only stored code should be the 84-1 error code but it isnt clear if it must be there from the walk through on the scanner. I went back into the menu and cleared the 84-21 code as it was the only error code I had and I know it doesnt want it there bc it said clear all codes that are not the 84-1 code. I decided that I would clear the code and even though 84-1 was not an error code that I had that I would follow the process for it to adjust the sensors anyway since I had changed out the two senors and never used a scanner to sync them to the car as it appeared from the walk through is necessary. I assumed when changing the wheel speed sensors and that they would essentially adjust or sync to the car and clear the code on their own and turn the error lights off. I disconnected the battery trying to accomplish that more times than I care to count and it didnt work. I assume as most sensors they identify themselves to the cars elec system and like most sensors do make the light go away that the bad sensor had set off. What was different was that even after clearing all codes before this code always returned. So its not just a matter of clearing the code but also appears to be that you have to have a tool that will sync the sensors to the car before it will go away for good.

The scanner tells you to park the car on level ground with wheels straight ahead and start the process. You confirm Yes when it is on level ground and it takes about 30 seconds for the scanner to automatically make the sensor adjustment. We have been driving the car all day and making hard turns and have reached 75mph and with no ABS / VSA or any other error lights coming on. It appears this worked for us. Prior to this when we reached 20 to 30 mph and after traveling just 500 feet or less the error light would appear after clearing all codes with the scanner.

Now, I do not know if this somehow get the lights to go away with the system still not working properly but I assume that is not the case.

The body shop tinkered with this and couldnt figure it out ans suggested I change the ABS module that ran several hundred dollars on its own.

(This post was edited by cmb7684 on Jan 8, 2017, 9:31 PM)

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